(;
AB[fc][id][jb][oc][pd][pf][pq][qo][cq][cp][cr][dr][cn]
AW[dd][df][do][dp][dq][fq][em][cl][kq][nc][nd][kc][kf]
C[Black plays.
Source: "Graded Go Problems", Volume 7, Kiseido Publishing];
LB[if:A][kb:B][pi:C][mq:D]
C[Hint: choose from A, B, C, or D.]
(;
B[if]
C[A good move.];
W[kh]
C[White reinforces the sandwiched group in the upper right];
B[ih]
C[Black extends further into White's left and bottom framework.]
)
(;
B[pi]
C[This move is the ideal extension on the right side, but ...];
W[if]
C[... White can jump here to expand his influence on the left, and even more at the bottom. This exchange of moves helped White more than Black.]
)
)